1. Field of Invention
This invention relates generally to semiconductor light-emitting devices and more specifically to reflective electrodes for semiconductor light-emitting devices.
2. Description of Related Art
Semiconductor light-emitting devices such as light-emitting devices (LED's) provide efficient sources of light and are more robust than incandescent light bulbs and fluorescent tubes. Advancements in LED technology and processing have facilitated the use of such devices as replacements for traditional lighting sources in commercial and residential lighting applications, for example.
LED's used for lighting applications generally include a reflective electrode that reflects a portion of the light generated by the device and also functions as a contact for providing a drive current to the device. The electrode material generally includes a metal. For some semiconductor materials it is difficult to find a metal for the reflective electrode that provides good electrical contact, good reflectivity, and good adhesion to the semiconductor material. For these semiconductor materials, a plurality of layers may be used to make up the reflective electrode. For example, the reflective electrode may include a first layer that provides good adhesion and good electrical contact, and a second layer that provides high reflectivity. Unfortunately, the first layer may also significantly attenuate the light before it reaches the second reflective layer, thus reducing the efficiency of the LED.
There remains a need for improved reflective electrodes for semiconductor light-emitting devices and improved processes for forming such electrodes.